Boosting photocatalytic ammonia synthesis performance over OVs-Rich Ru/W18O49: Insights into the roles of oxygen vacancies in enhanced hydrogen spillover effect

Synergistic water activation and nitrogen reduction process is significant to the photocatalytic ammonia synthesis reaction, in which the obtainment of active hydrogen (H*) from H2O dissociation and then transfer to N2 activation site is essential. Herein, the oxygen vacancies (OVs) enhanced hydrogen spillover is used to increase the H* transfer between the H2O activation site (Ru) and the N2 activation site (OVs-rich W18O49). Results shown that the OVs-rich Ru/W18O49 achieves high activity for NH3 production with a yield of 222.75 µmol‧g−1‧h−1, which is 5.60 folds of the OVs-deficient Ru/W18O49. Control experiments, characterization, and theoretical calculation made it clear that OVs played crucial roles in enhancing the hydrogen spillover by modifying the support's Gibbs free energy for hydrogen adsorption and lowering the barrier of H* migration. Finally, the detail mechanism was explained from a new perspective. This strategy may provide new insights for other hydrogenation reactions under mild conditions.